Since the middle of the twentieth century, television has grown from a novelty to a fixture in 99 percent of American households. Over time, the character of the medium also changed dramatically. Once offering only three principal broadcast networks, viewers' choices now may extend to more than a hundred channels. By 1999, 78 percent of homes with children and adolescents received at least …

Temper tantrums are disruptive behaviors in the form of angry outbursts that may be physical (hitting, biting, pushing), verbal (crying, screaming, whining), or persistent grouchiness and petulance. Tantrums are common in young children; up to 80 percent of two- and three-year-olds experience tantrums, and 20 percent have daily tantrums. Tantrums consistent with normal toddler development reflect …

The word "temperament" is used frequently in everyday speech. People will refer to another person, or even an object, as "temperamental." To social scientists, temperament is not a set of behaviors per se; it is not an ability, such as thinking, or a set of actions, such as playing. Instead, temperament is a behavioral style. It is not what a person does, but how that p…

Why are humans the way they are? Why is it that the abilities of children seem so different than those of adults? What can one do to help children become fully developed adults? These are the kinds of questions that theorists of human development try to answer. As it is easy to imagine from questions that are so broad, the answers theorists offer are equally broad, typically telling more about peo…

Theory of mind (ToM) is the understanding of the mental states of others, including their intentions, desires, beliefs, and emotions. Around the age of eighteen months, a child is able to understand the intentions of other people. This progresses until the ages of three to four-and-a-half when children begin to understand others' states of knowledge and belief. Janet Astington, a long-time …

The Three Mountain Task was developed by Jean Piaget and Bärbel Inhelder in the 1940s to study children's ability to coordinate spatial perspectives. In the task, a child faced a display of three model mountains while a researcher placed a doll at different viewpoints of the display. The researcher asked the child to reconstruct the display from the doll's perspective, select fr…

In the United States the provisions of Title V of the Social Security Act (SSA) have their origins in the First Maternity and Infant Act (or Sheppard-Towner Act) of 1921, a grant-in-aid program that provided federal funds to states for the establishment of maternal and infant welfare and hygiene agencies. Passed in 1935, Title V extended new funding to states to provide maternal and child health s…

Touch typically refers to the provision of tactile/kinesthetic stimulation to the newborn and young infant with the intended goal of facilitating early growth and development. Also known as "massage therapy," sensory experiences include stroking, holding, and passive movements. When applied to preterm infants who suffer from a lack of responsive, developmentally appropriate stimulati…

Toys, or objects whose main intended use is for play, have the potential to enhance development (creative building blocks) or to alter or hinder development (violent video games). Toys are the primary tools of childhood that allow children to extend their play beyond what can be done through imagination, voice, or action alone. The careful selection of toys by adults, as well as mediation of their…

Truancy is defined as unexcused absences from school without parents' knowledge. Causes of truancy may include social (e.g., peer pressure), family (e.g., low parental involvement, discord, abusive or neglectful environment), and individual factors (e.g., low IQ, drug or alcohol use, psychological disorder). As such, frequent truancy may signal other difficulties in a child's life. C…

Turner syndrome (genotype 45, XO) is a chromosomal anomaly arising from the failure of chromosomes to separate properly during meiosis (cell division in sex cells in which the chromosomal number is halved). In 60 percent of the cases an egg lacking an X chromosome (or a sperm lacking an X or Y chromosome) unites with a normal sex cell to produce a zygote, or fertilized egg, bearing a single X chro…

Throughout history, across all cultures, people have been fascinated with twins. In addition to interest in the close emotional ties and biological similarities that twins may share, reports of special twin languages and twin extrasensory perception (ESP) help people to explore ideas of what it means to be human. Twin language is a form of creole that some twins develop
and most outgrow at an ea…

Ultrasound is a method of assessing the fetus using low-frequency sound waves to reflect off fetal tissue. The ultrasound transducer produces ultrasound waves, which bounce off tissue at different speeds depending on its density. Most commercial ultrasound equipment emits energy that is much lower than the determined maximum safety standard. There are no known reports of fetal damage from conventi…

The lifeline of the fetus during its stage of intrauterine development, the umbilical cord averages 50 to 60 centimeters (20 to 23 inches) in length in a full term pregnancy and connects the fetus to the placenta. Contained within the cord are one umbilical vein, which transfers from the placenta the oxygen and nutrients necessary for fetal growth and development, and two umbilical arteries, which…

Some early video games, as well as many recent ones, were and are self-consciously educational and prosocial. Most would agree that video games of the 1970s, such as Pong, carried little more developmental risk than a game of table-tennis. The primary criticism at the time was that they fostered sedentary behavior in children. Many surveys of video games of the 1990s, however, tend to reveal both …

Violence in the United States is widely viewed, by policymakers and researchers, as an epidemic and a major public-health problem. Particularly in the wake of high-profile school shootings that occurred in the late twentieth century, the American public has shown increasing concern about violent adolescents and the harmful effects that exposure to violence has on children and adolescents. While hi…

Lev Semenovich Vygotsky was a developmental psychologist known for his sociocultural perspective. Born into a middle-class Jewish family in Orsha, Russia, Vygotsky's faith and social standing shaped many of his choices and views. Academically successful, Vygotsky entered Moscow University in 1913, where he studied law, being one of the few professions that allowed Jews to live outside restr…

While the effects of war on adults, and the countries in which they live, have long been studied and fairly well understood, the effects of war on children were largely ignored until the late twentieth century. Increased scrutiny by the press, "instant news," and twenty-four-hour cable coverage brought the ravages of war and children's circumstances into people's homes.…

Originally developed by David Wechsler in 1949, the third edition of the Wechsler Intelligence Scale for Children (WISC) was published in 1991. This standardized test is designed to measure children's (six to sixteen years of age) intellectual functioning in two broad areas. Verbal subtests require language skills similar to those used in schools, such as vocabulary and knowledge of general…

The history of welfare programs in the United States is a controversial one. Although many other nations in the world have welfare systems, some of which provide certain kinds of assistance for all citizens, the United States has always been divided in terms of what welfare means and who should receive welfare benefits. The welfare system in America underwent significant changes in the late 1990s …

Women, Infants, and Children (WIC) is a food assistance and nutrition program that provides supplemental food, nutrition education, and access to health care for pregnant women, women up to six months postpartum, women breast-feeding infants up to one year old, infants, and children under age five. Participants qualify based on nutritional risk and income at or below 185 percent of the federal pov…

The employment of mothers has been increasing to the point that it is now the modal pattern in the United States. In 1960, fewer than 30 percent of all mothers of children under age eighteen were in the labor force; forty years later, fewer than 30 percent were not in the labor force. Further, 64 percent of all married mothers with preschool children were in the labor force at the beginning of the…

Surrogate motherhood is a practice in which one woman (the surrogate mother) intentionally becomes pregnant and gives birth to an infant who will be adopted by another woman (the adoptive mother), as arranged by a legal contract prior to conception. The surrogate mother may be impregnated by artificial insemination with the adoptive mother's husband's semen or may have implanted in h…

Swaddling is the practice of binding or wrapping an infant in bands of cloth. An ancient custom, it is practiced in places as diverse as rural China, the American Southwest, Eastern Europe, and the Peruvian highlands. The reasons given for swaddling are also varied and include keeping the infant warm and protected in cold climates and at high altitudes, developing obedience, facilitating holding, …

Symbolic thought is the representation of reality through the use of abstract concepts such as words, gestures, and numbers. Evidence of symbolic thought is generally present in most children by the age of eighteen months, when signs and symbols ("signifiers") are used reliably to refer to concrete objects, events, and behaviors ("significates"). The hallmark of symboli…

English philosopher John Locke (1632-1704) proposed that the mind of the newborn infant is a tabula rasa, or blank slate, on which experience writes. Although research on infant cognition has shown that this view is too extreme, some psychologists (known as empiricists) continue to believe that development is primarily a process of learning from the environment. Other psychologists (known as nativ…

Tay-Sachs disease is a rare, inherited degenerative disorder of the nervous system associated with deficiency of the enzyme[.beta]-hexosaminidase A (HEXA). When the condition is present, a particular lipid, called a ganglioside, accumulates in the cells of the central nervous system. Functional and anatomical abnormalities result, and are clinically manifested by motor disturbances, seizures, spee…